after plain clean install, cannot launch demo game "Space Escape" due to "Error: unable to load package 'System.Threading'"

[MinnieTheMoocher]

I just did a clean install of Xenko 2.1.1.1 on Windows 7 / Visual Studio Community 2015.

The only action I took was to open the included Sample Game: "Space Escape".

The nuget installer window popped up, and downloaded some stuff.

In the end it failed with error message:
"Error: Unable to load package System.Threading"

[MinnieTheMoocher]

the same error happens when trying to create a new, empty game from scratch

[Kryptos-FR]

Check your proxy, firewall or antivirus settings. Something is blocking the ability to download packages from nuget.